function unzip_a_sensor(datename, senno, filedir, toPath, path7zip)

% 7zip is required
% datename: the file name for the .traffic
% senno: the name of the sensor to be extracted
% pathzip: the path of the 7z.exe, including the executable's name

if nargin==3
    path7zip = '"C:/Program Files/7-Zip/7z"';
end

if nargin==2
    % keep big raw data out of the source code folder
    toPath='../MN_data/extract';
end

cmd = sprintf('%s e %s/%s.traffic -o%s/%s %s.v30 -y > nul', path7zip, filedir, datename, toPath, datename, senno);
status = system(cmd);
cmd = sprintf('%s e %s/%s.traffic -o%s/%s %s.c30 -y > nul', path7zip, filedir, datename, toPath, datename, senno);
status = system(cmd);